The aim of this project is to develop immunosensors for cocaine, a representative drug of abuse and for cortisol in saliva which is a good indicator of adrenal function for clinical, psychiatric and physiological monitoring. Three types of sensors will be developed for each analyte including piezoelectric crystal, electrochemical and fiber optic detectors. The proposed technology will be based on utilizing immobilized antibodies in conjunction with the respective transducer. The performance of each sensor will be evaluated and compared with a reference method. The most promising sensors will be coupled to a flow- injection system and will be evaluated for continuous monitoring. The applications of the developed technology may be extended to include the monitoring of hormones, drugs, toxins and microorganisms. These sensors should, therefore, attract interest in a variety of scientific disciplines including clinical, industrial and environmental analysis. The developed technology could prove useful for several state and federal regulatory agencies.